Radar is an object-detection system that uses radio waves to determine the range, angle, or velocity of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. A radar transmits radio waves or microwaves that reflect from any object in their path. A receive radar, which is typically the same system as the transmit radar, receives and processes these reflected waves to determine properties of the object(s).
Currently, radar is being implemented in vehicles (automobiles), where vehicular radar signals may be used to detect forward/reverse object collisions as well as used for adaptive cruise control. Object collisions are detected by determining the distance the vehicle is from the object. For example, one way to obtain a distance measurement to the object is based on the time-of-flight: transmit a short pulse of radio signal (electromagnetic radiation) and measure the time it takes for the reflection to return. The distance is one-half the product of the round trip time (because the signal has to travel to the target and then back to the receiver) and the speed of the signal. Since radio waves travel at the speed of light, accurate distance measurement requires high-performance electronics.
Unfortunately, vehicular radar devices are costly to manufacture with tightly-coupled analog circuits and advanced antenna configurations on expensive process technology. Furthermore, radar is spectrally inefficient. In the standard radar processing architecture, for example, with frequency-modulated continuous-wave (FMCW) radar, the resolution is limited by the distance between the received digital samples. As a result, the spectrum bandwidth needs to be 150 MHz for meter-level accuracy. Additionally, current radar has no standardized capacity and/or smart coexistence, which are fundamental to communication systems. Finally, radar is insecure in that such devices are susceptive to spoofing since they do not accompany a fully-capable communication system to verify electromagnetic signal integrity. As a result, emergency braking and adaptive cruise control systems can be disrupted.
Hence, current vehicular radar systems are expensive to implement with spectrum inefficiency, lack of multiple access and minimal security.